这是在Ruby中正确使用符号吗? [英] Is this a correct use of symbols in Ruby?

问题描述

我正在使用第4行上的符号来应对代码挑战. 第4行的代码在做什么? 第4行没有正确使用符号吗?

I am working on a code challenge using symbols on line 4. What is the code on line 4 doing? Is line 4 not using symbols correctly???

 1  class NameThingy
 2
 3    def format_name(name) 
 4        return "#{name[:last]}, #{name[:first]}"
 5    end
 6
 7    def display_name(name)
 8       puts format_name(name)
 9    end
10
11  end


my_name = NameThingy.new#("Jessica Flores")
my_name.format_name("Jessica Flores")
my_name.display_name("Jessica Flores")

运行此命令时，出现以下错误消息:

test.rb:6:in `[]': can't convert Symbol into Integer (TypeError)
from test.rb:6:in `format_name'
from test.rb:17:in `<main>'

推荐答案

这是因为在您的情况下，name是String，而不是Hash.看一个相同的例子:

This is because name is an String in your case any how, not a Hash. Look one example for the same :

name = "good"
name[:a]
# `[]': no implicit conversion of Symbol into Integer (TypeError)

当您进行了my_name.format_name("Jessica Flores")， 名称 之类的方法调用时，该引用将保留对String实例"Jessica Flores"的引用.现在 String#[] 预期仅其参数为数字或 range 或 regexp 或 string .但不是符号.

When you did method call like my_name.format_name("Jessica Flores"), name, is then holding the reference to the String instance "Jessica Flores". Now String#[] expects only as its arguments either numeric number or range or regexp or string. But not symbol as per the documentation.

我将按照以下方式编写您的代码:

I would write your code as below :

class NameThingy

  def format_name(name)
    return name.split(" ").join(",")
  end

  def display_name(name)
    puts format_name(name)
  end

end

my_name = NameThingy.new
my_name.format_name("Jessica Flores")
my_name.display_name("Jessica Flores")
# >> Jessica,Flores

这篇关于这是在Ruby中正确使用符号吗?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！